Apparatus for electroplating crankshaft journals



April 1961 R. E. LUDWIG ETAL 2,979,452

APPARATUS FOR ELECTROPLATING CRANKSHAFT JOURNALS Filed Aug. 23, 1954 3Sheets-Sheet 1 INVENTORS K8| il mjwk RAJ) ATTORNEYS April 11, 1961 R. E.LUDW G ETAL 2,979,452

APPARATUS FOR ELECTROPLATING CRANKSHAFT JOURNALS Filed Aug. 25, 1954 5Sheets-Sheet 2 iiilmmurn 1N VENTOR S W a? M 8M 49 19W JQMJ J & Pm

ATTORNEYS April 1961 R. E. LUDWIG ETAL 2,979,452

APPARATUS FOR ELECTROPLATING CRANKSHAFT JOURNALS Filed Aug. 25, 1954 3Sheets-Sheet 5 INVENTORS APPARATUS FOR ELECTROPLATING CRANK- SHAFTJOURNALS Ralph E. Ludwig, Brokenstraw Township, Warren County, andDonald D. Dalrymple, North Warren, Pa., assignors to National ForgeCompany, Irvine, Pa., a corporation of Delaware Filed Aug. 23, 1954,Ser. No. 451,576

4 Claims. (Cl. 204-212) This invention relates to apparatus forelectroplating a metal such as chromium onto the pin and main journalstioning of crankshafts that have long been in service and have wornjournals. The method preferred for reconditioning is to grind the wornjournals where necessary to remove any badly worn spots in order toreestablish an essentially true cylindrical surface, then electroplatewith chromium to rebuild the diameter of the journal to a size slightlygreater than its original, and then finish grind to the exact originalsize. This results in a reconditioned shaft that is substantially aduplicate of a new one except that the surfaces of the journals are nowchromium instead of the original steel. Moreover the reconditioned shaftwill wear well since the chromium layer is very hard and standard sizedbearings can be used as distinguished from the alternative and lessdesirable method of grinding the worn journals to the next undersize andthen reassembling the crankshaft in the engine with correspondinglyundersized bearings.

In general the improved apparatus according to the present inventioncomprises a jig for supporting the crankshaft preferably in a horizontalattitude and rotating the same about its axis, an anode associated witheach journal, the latter functioning as a cathode, an electroplatingbath consisting of a solution of chromic acid in water in which theanode and cathode are immersed, and means for sending a direct currentthrough the bath from anode to cathode thus to deposit the chromium ontothe surface of the journal. However as distinguished from the generalclass of such apparatus heretofore developed wherein the entirecrankshaft is immersed in the electrolytic bath, the apparatus accordingto the present invention features independent baths or chambers for eachjournal on the crankshaft and through which the plating solution iscontinuously recirculated from a source of supply. Constant forcedrecirculation of the plating solution through each chamber is helpful inmaintaining a solution more uniform than can be obtained by generalagitation in a much larger bath in which the entire crankshaft issubmerged. Moreover the improved apparatus, employing individual bathsfor the journals, requires correspondinglyless of the plating solution,the system is closed thus avoiding loss of solution by evaporation'tothe surrounding atmosphere, continued forced ventilation of the room inwhich the apparatus is located becomes unnessa'ry which thus reflects asavings in heating costs for the room during winter, and the cost ofcollecting and exhausting the gases given off during the plating processis also reduced.

Independent electroplating baths for the various pin and main journalsas distinguished from a common bath for all journals also have otheradvantages. Independent baths enable independent control of the platingprocess 5a 5e and four crank pin journals Sf-Si, and the stub going onat each journal thus making it possible to control the thickness ofchromium deposit at each journal. Also by using transparent materialsuch as a plastic for the walls of each bath chamber one is able tobetter supervise the process at each journal at all times.

Another disadvantage inherent in the prior system wherein the entirecrankshaft is immersed in a tank containingthe plating solution andwhich the present invention avoids is that by immersion theentiresupporting structure for the crankshaft, including bearing supports,mercury contact and other parts, and even the carbonaceous deposits onthose surface areas of the crankshaft itself not masked off tend tocontaminate the plating solution and the solution in turn tends togradually deteriorate those parts. Also, those portions of thecrankshaft surface not masked olf and not being plated are exposed tothe hydrogen content of the plating solution which tends to make thesurface brittle. Any absorption of hydrogen into the fillet areas of thejournals is particularly to be avoided for here the shaft stresses arethe greatest and absorption of hydrogen can reduce the fatigue strengthof the metal by as much as 50%. Of course, the entire surface of thecrank-shaft except for those areas to be plated could be masked off byapplication of a temporary coating compound but this adds materially tothe overall cost of the reconditioning process and also does not giveassurance of positive and complete masking due in part to the physicalshape of the work.

A further objective of the invention is to provide an improved anodestructure which completely surrounds the journal (cathode), the anodebeing constituted by a helix of round bar stock which thereby assures auniform distance and hence uniform potential between anode and" allpoints on the surface of the journal as the latter revolves about itsaxis inside of the anode. Moreover the total area of the anode is madegreater than that of the journal (cathode) so as to prevent conversionof any of the chromium in the solution from its normal hexavalent stateto a' trivalent state which not only is of no value in the platingprocess but also tends to retard the same.

The foregoing as well as other objects and advantages inherent in theinvention will become more apparent from the following specification anddrawings which describe and illustrate one practical embodiment of theinvention. I

Fig. l of the drawings is a view in side elevation of the apparatus asdesigned for chromium plating a crankshaft having five main journals andfour crank pin journals.

Fig. 2 is a vertical transverse section taken on line 2-2 of Fig. 1.

Fig. 3 is a central vertical section of one of the housings shown inFig. 1 which surrounds a journal on the crankshaft to establish anelectroplating chamber, the. view being taken on line 3--3 of Fig. 4 anddrawn to a' larger scale in order to better show details of the struc-With reference now to the drawings in which like parts in the variousviews are designated by like reference numerals and to Figs. 1 and 2 inparticular, the apparatus for supporting the crankshaft is seen to becomprised of two longitudinally spaced pedestals 1, 2 containing sleevebearings in which stub shafts 3, 4 are rotatably mounted, the stubshafts being secured by suitable means to opposite ends of thecrankshaft 5 to be plated. The particular crankshaft illustrated hasfive main journals as-rates shafts 3, 4 being coaxial with the mainjournals, it will be seen that the crankshaft is thus arranged forrotation about the axis through the main journals. For rotating thecrankshaft there is provided a slow speed motor 6, the shaft of which iscoupled to one of the stub shafts such as the shaft 3 by a sprocket andchain drive 7.

As indicated at the outset, the present invention is characterizedprincipally by use of housings individual to the journals being platedand through which the plating solution, i.e. electrolyte, is circulatedas distinguished from immersion of the entire crankshaft in a tankcontaining the electrolyte. These housings, designated by numeral 8 aremade in two parts so as to enable them to be fitted around and enclosethe journals and will be described later in further detail. Below thecrankshaft and extending parallel therewith is a trough-like tank whichserves to catch any spillage of the electrolyte from the journalhousings and return the same to the circulating system for theelectrolyte. The housings 8 are made fluid tight but there is bound tobe some spillage as the housings are removed and replaced. Tank 9 alsoserves as a support for manifolds 1043 extending along the outsidethereof which serve to collect the electrolyte after it has passedthrough the housings 8 and to collect the discharge gases that are givenoff during the plating process. The electrolyte return manifolds 1011,preferably of rigid, plastic material unaffected by the electrolyte, arearranged along opposite sides of tank 9 and lead to the intake of acentrifugal pump 14. Connected to these manifolds are flexible conduits15, 16, also preferably made of plastic material not affected by theelectrolyte, which lead to the electrolyte outlets 17, 18 at oppositesides of the upper end of housings 8. This is best seen in Fig. 4. In asimilar manner, other flexible plastic conduits 19, 20 connect the gasdischarge outlets 21, 22 to the manifolds 12, 13 on tank 9 by which thegases are conveyed away through exhaust conduit 23.

Extending upwardly from each of the electrolyte housings 8 is anelectrically conductive rigid pipe 24 which serves to both support andcarry current to the anode 25 in each housing, and also as a conduit tobring the electrolyte into the housing. As shown in Fig. 2, a flexibleconduit 26, also of flexible plastic material, extends from the top ofeach pipe 24 into a supply or inlet manifold 27 made of rigid plasticmaterial and secured to a support 28 made of insulating materialextending parallel with the tank 9. The supply manifold is connected toa bottom outlet 29a of a storage tank 29 for the electrolyte and thetank 29 is located above the manifold 27 to establish gravity flow ofthe electrolyte to the several housings 8. The outlet from theelectrolyte pump 14 connects with a pipe 30 leading to an inlet 29blocated at the top of storage tank 29.

It will thus be seen that the electrolyte 31 is caused to circulate in aclosed system from storage tank 29 through manifold 27, conduits 26 andpipes 24 into the several housings 8, out of the latter via conduits 15,16,

into the return manifolds 10, 11, back to pump 14 and from the lattervia conduit 30 back into the tank 29 for recirculation.

In order to assure a good circulation of the electrolyte through thehousings 8 it will be seen from Fig. 4 that baffie plates 32, 33 arearranged at each side of the anode 25 between the latter and theelectrolyte outlets '17, 18. Thus the electrolyte entering the housing 8through pipe 24 is caused to travel downward through the anode 25 andaround the crankshaft journal to the bottom of the housing, then underthe bottom edge of baffles 32, 33 which are spaced from the bottom wallof the housing and then upward through the space between baffles 32, 33and theside walls of the housing and out through the outlets 17 and 18.The course of fluid flow-is indicated by the arrows.

Each of the baffles 32, 33 is preferably provided with a small vent hole34 through the same at approximately.

the level of the outlets '17, 18 to prevent syphoning of the electrolytethrough these outlets.

The anode 25 is preferably constituted by a helix of round bar stockwhich is cut along a diameter after it has been wound to thus form anupper section 25a and a lower section 25b, the turns of each sectionbeing held in rigid spaced relationship by bars 35, 36 that are weldedin place at the upper and lower halves respectively of the helix beforecutting. Pipe 24 is secured to top bar 35 in such manner as will notblock free flow of electrolyte out of the bottom end thereof and thussupports the upper half 25a of the anode. In a similar manner, a solidrod 37 of electrically conductive material is secured to bottom bar 36to thus support the lower half 25b of the anode. Pipe 24 is in turnsecured to the top wall of housing 8 at its pass through point and rod37 is secured to the lower wall of housing 8 at its pass through point.As stated previously, the area of the helical anode 25 is made greaterthan that of the crankshaft journal so as to prevent any of the chromiumin the plating solution from being converted from its normal hexavalentstate to a trivalent state. The latter is of no value in the platingprocess and also tends to retard the same. Moreover, due to the helicalconfiguration or the anode, a uniform potential between all points onthe anode and the crankshaft journal as the latter rotates is assured.

The housings 8, preferably of transparent material such as a plastic,are each divided horizontally into upper and lower half sections 8a, 8bto form a fluid tight fit around the crankshaft journals and are heldtogether by means of clamps 38, 39 at each side 'of the housing. Toavoid undue complexity in the drawings, these clamps have been omittedfrom Figs. 1 and 2. A plastic is preferred for the housings 8 since itis not adversely affected by chromic acid and, being transparent, one isable to observe the plating action at each journal. Baffles 32, 33 arelikewise divided horizontally into upper and lower sections 32a, 32b and33a, 33b, the upper baffi'e sections 32a, 33a being secured to the sidewalls of the upper housing section 811, and the lower baffle sections32b, 331) being secured to the side walls of the lower housing section8b.

The upper housing section 8a also preferably includes a wiper blade 50of a plastic material that is comparatively stiff and which extendsbetween the side walls of the housing section 8a in the longitudinaldirection of the crankshaft journals inside of the upper anode section25a in such manner that the lower edge thereof which is toothed at 50aengages the surface of the journal to establish a wiping action as thejournal rotates thus brushing off any gas bubbles or foreign particleswhich otherwise would tend to adhere to the surface of the journal andinterfere with a uniform deposit of chromium on the journal.Consequently the upper housing sections 8a are each structurally unitedwith pipe 24, the upper anode section 25a, the upper baflle sections32a, and 33a and wiper blade 51), and the lower housing sections 8b areeach structurally united with rod 37, the lower anode section 25b andlower baflle sections 32b, 33b. When the upper and lower halves of thehousing are assembled, as shown in Fig. 4 the two halves of the anode 25will meet at a uniform distance from the journal being plated and willbe concentric with the latter.

In order to better feed current to the lower anode section 25b, a strap40 of conductive material is connected by clamps 41 to the pipe 24 androd 37.

Current is supplied to the anodes 25 through the pipes 24 and each ofthe latter is connected by a flexible conductive strap 42 to a bus bar42 extending longitudinally of the support 28 and secured to the ends ofthe latter by means of insulating members 44.

With reference to Fig. 2 it will be seen that the support member 28 isprovided with a horizontal portion containing a plurality of slots 28ain vertical alignment with the pipes 24 and through which the pipes 24extend.

When the "crankshaft 5 is rotated on its axis, the pipes 24 a'ndhousings 8 associated with the main journals remain stationary. Howeverthose pipes 24 and housings 8 associated with the crank pin journalsdescribe a planetary motion. The function served by the slots 28a is toguide the pipes 24 and prevent the housings from rotating with thecrankshaft.

As previously explained, the electroplating is done with direct currentand the circuit is shown in a schematic manner in' Fig. "1, the sourceof direct current being indicated by terminals 45 and the conventionaland symbols. A lead 46 extends from the terminal to bus bar 43,and-hence to anodes 25, and another lead '47 extendsfrom the terminaltoa mercury type contact device 48 associated with the stub shaft 4, thelatter being rotated in a pool of mercury to assure good electricalcontact to the crankshaft and thereby to thejournals 5a- 5i whichfunction as cathodes in the plating process.

'In operation, the crankshaft to be plated is arranged as shown in Fig.1 for rotation about alongitudinal axis through the center'of the mainjournals. The housings 8 together with the anodes 25 supported thereinand pipes 24 are then mountedon the pin and main journals, and theflexible tubes 15, 16, 19, 20 and 26 are connected to the manifolds -13and 27. Straps 42 are then attached to the bus bar 43 thus electricallyconnecting the pipes 24 and anodes 25 to the bus bar and positiveterminal of the direct current source. The electrolyte 31 is nowadmitted into the manifold 27 from storage tank 29 and flows outwardlyfrom manifold 27 through valves 53 at each lateral outlet to conduits26, downwardly through the pipes 24 into the anode housings 8 andfilling the latter to the level of the overflow outlets 17, 18.

As will be seen best from Fig. 3, the sides of the housings 8 fittightly about the end portions of the journals and hence prevent any ofthe electrolyte from getting to the fillet areas 5k at the junction ofthe cheek plates 5m and the journals. As explained at the outset this ismost important since any absorption of hydrogen from the electrolyteinto these areas where the crankshaft stresses are greatest tends tomake the surface more brittle which is reflected by a reduction infatigue strength and hence the safety factor at the very places where itcan least be tolerated.

Motor 6 is now started, as is also the pump 14, and the chromium platingprocess now begins as the crankshaft slowly rotates. The electrolytecirculates continuously in and out of the anode housings and theelectrolyte will remain at substantially the level indicated in Fig. 4i.e. slightly above the vents 34 in baffles 32, 33. The helicalconfiguration of the anode 25 assures a uniform electrical potentialbetween the anodes and all points on the surface of the journal as thelatter rotates. Being transparent, one is enabled to supervise theplating process at each journal at all times and it becomes quite asimple matter to inspect any journal whenever desired by shutting 01?valve 53 thus to stop the flow of electrolyte into the anode housing andthen removing the latter. Moreover independent treatment of the journalsmakes it possible to stop the plating process at any journal at any timewithout interfering with the plating process going on at the otherjournals. This feature thus provide-s independent control over thethickness of chromium deposit at each journal and cannot very well beduplicated with apparatus of the type wherein the entire crankshaft issubmerged in a tank containing the electrolyte.

In conclusion, it is to be understood that the particular embodiment ofthe invention as hereinabove described and illustrated in the drawingsis to be considered typical rather than limitative of the scope of theinvention as defined in the appended claims, a basic concept of whichresides in the use of a combined anode and electrolyte housing for eachjournal, and a closed system for continous circulation of theelectrolyte through the several housings. Consequently variousmodifications of structural details such as for example the arrangementof in lets and outlets on the housings for the electrolyte, the anodestructure and the electrolyte manifolding may be resorted to withouthowever departing from the spirit and scope of the invention.

We claim:

1. Apparatus for electroplating a crankshaft journal comprising ahousing surrounding only the journal por' tion of said crankshaft, saidhousing including aligned openings in the sidewalls thereof forreceiving the journal, and said housing being sectionalized at saidopenings to permit installation and removal with respect to the journal,an arcuate anode within said housing main,

I tained in concentric spaced relation to said journal, said anode beingsectionalized to. permit installation and re-'. moval with respect tothe journal, an electrically con-' ductive pipe passing through a wallof said housing, said pipe being connected to said anode and alsoconstituting an inlet for electrolyte into said housing, arr outlet onsaid housing for removing electrolyte therefrom, means for circulatingelectrolyte through said housing between said inlet and outlet; andmeans for rotating said journal.

'2; Apparatus for electroplating a horizontally disposed crankshaftjournal comprising a housing surrounding only the journal portion ofsaid crankshaft, said housing including aligned openings in thesidewalls thereof for receiving the journal, and said housing beingsectionalized at said openings to permit installation and removal withrespect to the journal, an arcuate anode within said housing maintainedin concentric spaced relation to said journal, said anode beingsectionalized to permit installation and removal with respect to thejournal, an electrically conductive pipe secured to said anode and alsoconstituting an inlet for electrolyte at the top of said housingintermediate the side walls thereof, an outlet for electrolyte throughthe upper portion of a side wall of said housing, a vertical bafile insaid housing between said inlet and side wall whereby to establish apath for electrolyte flow downward from said inlet to the bottom portionof said housing and thence under said battle and upward between saidbathe and side wall to said outlet, means for circulating electrolytethrough said housing, means for rotating said journal, and meansrestraining said housing and anode against rotation.

3. Apparatus for electroplating the journals of a crankshaft comprisingmeans for supporting said crankshaft for rotation in a horizontalattitude, means for rotating said crankshaft, a trough extendinglongitudinally of and below said crankshaft, housings individual to andsurrounding each journal portion only of said crankshaft, each saidhousing including aligned openings in the sidewalls thereof forreceiving its corresponding journal, and each said housing beingsectionalized at said openings to permit installation and removal withrespect to its 'corresponding journal, an arcuate anode within eachhousing maintained in concentric spaced relation to said journal, eachsaid anode being sectionalized to permit installation and removal withrespect to its corresponding journal, means restraining said housingsand anodes against rotation, an inlet and outlet for electrolyte to andfrom each housing, an outlet manifold extending along said trough and towhich the outlets on said housings are connected, an inlet manifoldlocated at a level above said housings and to which the inlets on saidhousings are connected, a storage tank for electrolyte located at alevel above said inlet manifold and to which said inlet manifold isconnected, a pump having its intake side connected to said outletmanifold and its discharge side connected to said tank, an outlet oneach said housing for gas, and a gas collecting manifold extending alongsaid trough and to which said gas outlets are connected.

4. Apparatus for electroplating the journals of a crankshaft comprisingmeans for supporting said crankshaft for rotation in a horizontalattitude, means for rotating 5 said crankshaft, a trough extendinglongitudinally of and below said crankshaft, housings individual to andsurrounding each journal portion only of said crankshaft, each saidhousing including aligned openings in the sidewalls thereof forreceiving its corresponding journal, and each said housing beingsectionalized at said openings to permit installation and removal withrespect to its corresponding journal, an arcuate anode within eachhousing maintained in concentric spaced relation to said journal, eachsaid anode being sectionalized to permit installation and removal withrespect to its corresponding journal, means restraining said housingsand anodes against rotation, an electrically conductive pipe secured tosaid anode and also constituting an inlet for electrolyte into eachhousing through the top wall thereof, outlets for electrolyte extendingthrough the upper portion of opposite side walls of each housing,vertical bafiles in each housing between the said opposite side wallsthereof and said inlet whereby to establish paths for flow ofelectrolyte downward from said inlet to and under the lower edges ofsaid baffles and thence up between said bafl les and opposite side wallsto said outlets, an outlet manifold extending along each side of saidtrough and to which the outlets on said housings are connected, an inletmanifold located at a level above said housings and to which the inletson said housings are connected, a storage tank for electrolyte locatedat a level above said inlet manifold and to which said inlet manifold isconnected, and a pump having its intake side connected to said outletmanifolds and its discharge side connected to said tank.

References Cited in the file of this patent UNITED STATES PATENTS1,757,235 Clark et al. May 6, 1930 v1,872,290 Hitner Aug. 16, 19321,880,382 Garling Oct. 4, 1932 1,955,046 Baumann Apr. 17, 1934 2,431,949Martz Dec. 2, 1947 2,491,925 Lazaro Dec. 20, 1949 2,710,834 VrilakasJune 14, 1955 FOREIGN PATENTS 925,912 France Apr. 14, 1947 117,302Australia July 22, 1943

1. APPARATUS FOR ELECTROPLATING A CRANKSHAFT JOURNAL COMPRISING AHOUSING SURROUNDING ONLY THE JOURNAL PORTION OF SAID CRANKSHAFT, SAIDHOUSING INCLUDING ALIGNED OPENINGS IN THE SIDEWALLS THEREOF FORRECEIVING THE JOURNAL, AND SAID HOUSING BEING SECTIONALIZED AT SAIDOPENINGS TO PERMIT INSTALLATION AND REMOVAL WITH RESPECT TO THE JOURNAL,AN ARCUATE ANODE WITHIN SAID HOUSING MAINTAINED IN CONCENTRIC SPACEDRELATION TO SAID JOURNAL, SAID ANODE BEING SECTIONALIZED TO PERMITINSTALLATION AND REMOVAL WITH RESPECT TO THE JOURNAL, AN ELECTRICALLYCONDUCTIVE PIPE PASSING THROUGH A WALL OF SAID HOUSING, SAID PIPE BEINGCONNECTED TO SAID ANODE AND ALSO CONSTITUTING AN INLET FOR ELECTROLYTEINTO SAID HOUSING, AN OUTLET ON SAID HOUSING FOR REMOVING ELECTROLYTETHEREFROM, MEANS FOR CIRCULATING ELECTROLYTE THROUGH SAID HOUSINGBETWEEN SAID INLET AND OUTLET, AND MEANS FOR ROTATING SAID JOURNAL.